The forest area in Portugal occupies about 3.5 million hectares, being the Pinus pinaster and Eucalyptus globulus stands the most important and more concentrate in the North and Center of Portugal. As consequence, the quantity of ashes and other wastes from the boilers is estimated in 100 thousandths tones in the thermoelectric plants managed by the pulp and paper industry. This quantity of ashes depends of the biomass quality and the boiler technology (grate or...